Safe and arming mechanism for fuze



May 7, 1968 G. WEBB SAFE AND ARMING MECHANISM FOR. PUT-R Filed July 5,1967 INVENTOR. GEORGE WEBB ATTORNEY.

United States Patent Ofice 3,381,613 Patented May 7, 1968 3,381,613 SAFEAND ARMING MECHANISM FOR FUZE George Webb, Richmond, Ind., assignor toAvco Corporation, Richmond, Ind., a corporation of Delaware Filed July3, 1967, Ser. No. 650,818 3 Claims. (Cl. 10270.2)

ABSTRACT OF THE DISCLOSURE This is a mechanism for incorporation in afuze of the proximity type, powered by a thermal battery. The fuze isadapted for use in a bomblet. The mechanism includes a thermal batteryand an electric detonator and its unarmed condition is characterized asfollows: first, by a short-circuit on the detonator; second, bymisalignment of a lead on an electric detonator. The fuze is armed byspin, arming weights releasing a slider, which impacts a stab primeragainst a stab firing pin, the resultant percussive forces drivinganother firing pin into the thermal battery to actuate the same.Additionally, the movement of the slider aligns the lead with theelectric detonator and removes the short-circuit from the detonator,whereby the fuze is fully armed.

Field of the invention The principal object of the invention is toprovide a safe and arming mechanism for spin armed missiles and thelike.

Another object of the invention is to provide a fuze safe and armingmechanism of the slider type, which utilizes excess energy provided bythe motion of the slide to cause an internal explosion, which in turn isutilized to perform arming functions at an energy level which isrelatively high as compared to the energy level involved in the motionof the slider.

A further object of the invention is to provide a fuze safe and armingmechanism which responds to spin to perform an arming function and thensets up a high energy process, which high energy is utilized to completethe arming sequence.

It is a general object of the invention to provide a fuze mechanism forperforming all arming functions, in cases in which the mechanical forcesavailable due to spin or gravitation are not adequate.

Description of the drawings For a better understanding of the invention,together with other and further objects, advantages and capabilitiesthereof, reference is made to the following description of the appendeddrawings, in which:

FIG. 1 is a longitudinal sectional view as taken along section lines 11of FIG. 2, looking in the direction of the arrows; and

FIG. 2 is an end view of the fuze arming mechanism in accordance withthe invention.

Detailed description of the invention The fuze in which the presentinvention is of particular utility is powered by a thermal battery andincludes electrical circuitry (not shown) which is energized by thethermal battery to fire an electrical detonator. This occurs when thefuze reaches the vicinity of a target, the action being that of thewell-known proximity fuze which need not be described in detail.

In the unarmed condition of the fuze here shown, a switch imposes ashort-circuit across the electrical detonator, for safety reasons.Further, in the unarmed condition, a slider holds a lead out ofalignment with the electrical detonator so that the firing train isbroken. The lead is not in alignment with the detonator until the slidermoves in the armed position. This is an additional safety feature. Inthis fuze, the slider moves not only to align the lead and theelectrical detonator but also to remove the short-circuit from thedetonator. The slider performs two additional functions. First, as itmoves into the armed position, it carries a primer against a firstfiring pin of the stab type, which drives a second firing -pin into athermal battery. The slider is thereby locked in the armed position andthe thermal battery is activated.

Referring now to the drawings, attention is first invited to the armingmeans or slider 10, 11. The slider comprises a brass weight member 10and an aluminum carrier member 11, suitably mechanically joined, asindicated at 12. The carrier is transversely bored near its upper end toprovide a mounting for a lead 13 disposed therewithin. The carrier isformed near its central axis with a cylinder for retention of the firingpin 14 and this cylinder is in communication with a radially extendingbore in which a stab primer 15 is mounted. Support for the operatingparts of the fuze is provided by a housing frame 16, which is generallyof well-shaped configuration. The frame is disposed within a cup 17. Theframe is further formed with a port 18 in communication with anelectrical detonator 19. This detonator is normally short-circuited by aswitch 21. The frame is formed to secure in position the detonator and athermal battery 20. The carrier and the fuze housing are suitably formedto provide for the engagement, release and sliding movement of armingweights 22 and 23. The weights 22 and 23 are normally biased intolatching position by arming weight springs 24 and 25. A firing pin 26 ofthe stab type is mounted on a flange portion of the frame 16. It extendsinwardly in a radial direction and is in alignment with stab primer 15.

The discussion now proceeds to a typical cycle of operation. As thebomblet in which the fuze is installed attains the required thresholdrate of spin, centrifugal force acting on the arming weights 22 and 23overcomes the force of the arming springs 24 and 25 so that the weights22 and 23 move outwardly, disengaging from and freeing the slider 10,11. The slider is freed and the slider moves in a direction transverseto the axis of the fuze into the armed position, placing the lead 13 inline with the detonator 19. Additionally, the slider drives the stabprimer 15 into the firing pin 26. As the stab primer 15 strikes thefiring pin 26, the energy in the primer 15 is released and it causes thefiring pin 14 to be driven into the thermal battery 20. This actionlocks the slider 10, 11 in place.

Switch 27 is normally in a short-circuiting position with respect to theelectrical detonator 19 and this switch has an arm 21 which is biased insuch a manner that when the slider frees that arm the short-circuit isremoved from the electrical detonator 19. That is, the switch 27 ismounted on the frame 16 and the arm 21 is so biased as to exert a thrustagainst the carrier member 11. When the carrier moves to the armedposition the switch arm 21 turns counter-clockwise (FIG. 2) and opensthe switch 27.

While there has been shown and described what is at present consideredto be the preferred embodiment of the invention, various changes andmodifications may be made without departing from the invention asdefined by the appended claims.

What is claimed is:

1. In a safe and arming mechanism for a fuze of the type having athermal battery and an electric detonator, the combination of:

a frame formed to support said thermal battery and detonator,

a slider mounted for dis-placement transverse to the longitudinal axisof said mechanism,

a firing pin carried by the slider,

a stab primer carried by the slider,

21 firing lead carried by the slider,

another firing pin mounted on the frame,

locking means for normally retaining the slider in such position thatthe lead is misaligned with the detonator and the stab primer is alignedwith but out of contact with said other firing pin and the first firingpin is misaligned with the detonator,

and slider locking means responsive to spin to be released to permitdisplacement of the slider in response to centrifugal force to aposition Whereat the said other firing pin is impacted by the primer,thereby driving the first-mentioned firing pin into the thermal batteryto actuate same, said displacement bringing the lead into alignment withthe detonator so as to accomplish arming.

2. The combination in accordance with claim 1 and position.

References Cited UNITED STATES PATENTS Dell et a1. 102-70.2 Brode10270.2

Burrell 102-70.2

Crozier 102-702 Crozier 10270.2

BENJAMIN A. BORCHELT, Primary Examiner.

T. H. WEBB, Assistant Examiner.

